Process, apparatus and system for creating extruded material having color effects and products made with extruded material created with same

ABSTRACT

A process and associated system for creating color effects using extrudable material, such as plastic and metal for example, are presented. Flows of first and second viscous materials of respective colors are provided and then combined in a predetermined pattern to form a stream of combined viscous material. A dynamic mixer is the then used to apply a predetermined dividing, overturning and combining motion to the stream of combined viscous material to partially mix the first viscous material and the second viscous material, such that upon exiting the dynamic mixer, the first material of the first color and the second material of the second color form a color pattern in the stream of combined viscous material. The dynamic mixer has elements configured for acquiring a specific radial orientation in a range of radial orientations that may be varied during the application of the dividing, overturning and combining motion to the stream of combined viscous material to cause variations in the color pattern in the stream of combined viscous material. Sheets of extruded material may be created using such process and system and used in the manufacturing of many different products including, but not limited to, kayaks, stand-up paddle boards, garden furniture and many others. In some embodiments, the sheets may be characterized by color bands extending diagonally with reference to a longitudinal extent of the sheet.

CROSS-REFERENCES TO RELATED APPLICATION

This application claims the benefit of priority under 35 U.S.C. 119(e)based upon U.S. provisional application Ser. No. 62/661,377 filed Apr.23, 2018. The contents of the above referenced application areincorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates generally to the field of extrusionprocesses and extruded materials created using such processes, includingfor example plastic or metal materials. More specifically, the presentinvention relates to processes and associated apparatuses and systemsfor creating extruded materials (such as for example but without beinglimited to sheets and tubes) having color effects as well as to productsmade with extruded materials having color effects created using suchprocesses.

BACKGROUND

Extrusion processes are commonly used in a variety of differentindustries, and with a multitude of different types and grades ofmaterial, for forming and shaping these materials into articles.

Extruded products, whether plastic, metal or some other material, areoften uniform in color. In some cases, the extruded products are formedof several layers of material, including one or more visible, outerlayers and one or more hidden, inner layers, where these layers maydiffer in color.

In today's competitive market place, it is important for companies tohave an edge that distinguishes their product from a competitor'sproduct. One way to create a product that distinguishes itself from acompetitor's product is to provide the product with an aestheticallypleasing and/or original appearance. Consumers are typically attractedto products having a visually appealing look.

In the field of extruded products, one method for giving the endproducts a visually appealing look is to create special color effects inthe material of the product. Existing methods for producing coloreffects in extruded material, such as plastic for example, includelamination techniques, wherein multiple different layers of coloredmaterial are joined together to form a multi-colored sheet, andimprinting techniques wherein an imprinted film is adhered to thematerial. Unfortunately, these processes require treating the materialafter it has been extruded and formed. This can be both costly and timeconsuming.

Other methods, such as the one described for example in U.S. Pat. No.7,204,944, allow producing color effects in the extruded material bycombining flows of viscous material of multiple colors and using astatic mixer during the extrusion process to form a stream of viscousmaterial. The contents of the aforementioned documents are incorporatedherein by reference. While approaches of the type described above mayallow creating extruded material having a pleasing and original visualappearance, the visual effects that may be produced tend to be limited.Another approach for obtaining other original color effects is describedin U.S. patent application publication no. US20170182697 A1. Thecontents of the aforementioned documents are incorporated herein byreference. However, in this case as well, the visual effects that may beproduced also tend to be limited. In order to attract the attention ofconsumers, it is desirable to create a variety of original color effectsin extruded materials include some that may differ from those that maybe created by methods of the type proposed in U.S. Pat. No. 7,204,944and U.S. patent application publication no. US20170182697 A1.

As such, a need exists in the industry to provide methods for producingvisually appealing color effects in extruded material, such as plasticand metal.

SUMMARY

In accordance with a first aspect, a process for creating color effectsusing extrudable material is described. The process comprises:

-   -   a) providing a flow of a first viscous material of a first        color;    -   b) providing a flow of a second viscous material of a second        color different from the first color;    -   c) combining in a predetermined pattern the flow of the first        viscous material and the flow of the second viscous material to        form a stream of combined viscous material, the stream        comprising a first band of the first color and a second band of        the second color, the second band being adjacent to the first        band;    -   d) feeding the stream of combined viscous material through a        dynamic mixer configured for applying a dividing, overturning        and combining motion to said stream of combined viscous material        to partially mix the first viscous material and the second        viscous material, such that such that upon exiting the dynamic        mixer, the first material of the first color and the second        material of the second color form a color pattern in the stream        of combined viscous material, wherein said dynamic mixer has        elements configured for acquiring a specific radial orientation        in a range of radial orientations, said process comprising        varying the specific radial orientation of the elements of the        dynamic mixer during the applying of the dividing, overturning        and combining motion to the stream of combined viscous material        to cause variations in the color pattern in the stream of        combined viscous material.

In some specific practical implementations, the first band and secondband may remain in the stream of combined viscous material, which mayfurther include a third band of a third color that is different from thefirst and second colors. The first band, the second band and the thirdband may be twisted with one another in the stream of combined viscousmaterial as a result of the varying the specific radial orientation ofthe elements of the dynamic mixer.

In some specific implementations, the varying the specific radialorientation of the elements of the dynamic mixer may include performinga rotation of the elements of the dynamic mixer by a pre-determinedamount to vary the specific radial orientation of the elements of thedynamic mixer during the applying of the dividing, overturning andcombining motion to the stream of combined viscous material. Therotation may be performed repeatedly over time, either at regular(fixed) or variable time intervals. The angle of rotation may varywidely for example it may be greater than 0° and less than or equal to360°; between 30° and 130°; between 45° and 110°. In a non-limitingexample, the angle of rotation is about 90°. In other specific practicalnon-limiting implementations, the pre-determined rotation amount may bea rotation of about 45°, 135° or 180°. It is to be appreciated that therotation may be performed clock-wise or counter clock-wise and may infact alternate between one or more clockwise rotations and one or morecounter clock wise rotations in order to produce different colorpatterns in the stream of combined viscous material.

In some specific implementations, the varying the specific radialorientation of the elements of the dynamic mixer may include causing therotational position to vary substantially continuously over a timeinterval. The rotational position of the dynamic mixer has a rate ofchange over time defining a rotational speed of the dynamic mixer, whichmay either remain substantially constant over time or which may insteadvary.

In a specific, non-limiting example of implementation, processes of thetype described above may be implemented in a system for manufacturingextruded plastic sheets. The system may include a die, a feed block, adynamic mixer and at least two extruders. The extruders may each beconfigured to mix and heat plastic granules, for producing a generallyhomogeneous, viscous plastic mixture. In the context of the presentinvention, at least two of the extruders produce plastic mixtures ofdifferent colors and of different viscosities. The feed block isconfigured to combine the flows of viscous plastic released by thedifferent extruders into a single stream of combined viscous material.The single stream of viscous plastic generated by the feed block maythen be fed through the dynamic mixer pipe. The dynamic mixer pipe isconfigured to act on the single stream of combined viscous material topartially mix the stream and create a color pattern in the stream ofcombined viscous material. The die receives the partially mixed streamof combined viscous material and may be configured to shape the streaminto its final product form, such as a sheet or a tube, among many otherpossibilities. In some implementation, the stream of combined viscousmaterial may optionally be passed through a second feed block to combinethe partially mix the stream with one or more additional streams ofviscous material before it is sent to the die.

In accordance with another aspect, a system for creating color effectsusing extrudable material is provided, the system comprising:

-   -   a) a first extruder for providing a flow of a first viscous        material of a first color;    -   b) a second extruder for providing a flow of a second viscous        material of a second color different from the first color;    -   c) a feed block for combining the flow of the first viscous        material and the flow of the second viscous material to form a        stream of combined viscous material, the stream comprising a        first band of the first color and a second band of the second        color, the second band being adjacent to the first band;    -   d) a dynamic mixer for applying a dividing, overturning and        combining motion to said stream of combined viscous material to        partially mix the first viscous material and the second viscous        material, such that such that upon exiting the dynamic mixer,        the first material of the first color and the second material of        the second color form a color pattern in the stream of combined        viscous material, wherein said dynamic mixer has elements        configured for acquiring a specific radial orientation in a        range of radial orientations;    -   e) an electronic controller in communication with said dynamic        mixer, said electronic controller being configured for varying        the specific radial orientation of the elements of the dynamic        mixer during the applying of the dividing, overturning and        combining motion to the stream of combined viscous material to        cause variations in the color pattern in the stream of combined        viscous material.

In some specific practical implementations, the system may furthercomprise a die for receiving the stream of combined viscous materialfrom the dynamic mixer, the die being configured for forming the streamof combined viscous material into a sheet or into a tube.

In some specific practical implementations, the system may furthercomprise at least one additional extruder for providing at least oneadditional flow of a third viscous material and a combining device forcombining the stream of combined viscous material released by thedynamic mixer with the at least one additional stream of the thirdviscous material provided by the at least one additional extruder. Thecombining device may be configured for forming a co-extruded streamhaving at least two layers using the stream of the third viscousmaterial and the stream of combined viscous material.

In accordance with another aspect, a process for manufacturing a plasticarticle comprising color effects is presented. The process comprisesmolding two or more of the manufactured sheets of extruded materialusing thermoforming to shape the two of more manufactured sheets into akayak shape, at least one of the two or more of the manufactured sheetshaving color effects created using a process of the type describedabove.

In specific practical implementations, another one of the two or more ofthe manufactured sheets may have a uniform color or, alternatively, mayalso have color effects created using a process of the type describedabove.

In specific practical implementations, the process may be suitable foruse during manufacturing of many different types of products including,but without being limited to, kayaks, sleds and stand-up paddle boardsamongst many others.

In accordance with another aspect, a plastic article is providedcomprising an extruded sheet made of a plurality of materials ofdifferent colors. The sheet is formed into at least a portion of theplastic article and has a surface presenting color effects includingcolor gradation effects resulting from combinations of the viscousmaterials, wherein sections of the extruded sheet taken along alongitudinal axis extending along the extruded sheet are characterizedby undulating color bands oriented along a longitudinal extent of thesheet.

In specific practical implantations, the plastic article may be astand-up paddle board or a kayak.

In accordance with another aspect, a sheet of extruded material made ofa plurality of viscous materials of different colors is provided. Thesheet has a surface presenting color effects including color gradationeffects resulting from combinations of the viscous materials such thatsections of the extruded sheet taken along a longitudinal axis extendingalong the extruded sheet are characterized by undulating color bandsoriented along a longitudinal extent of the sheet, which may in somecases create a wave-like pattern.

In accordance with another aspect, a kayak is provided comprising anextruded sheet made of a plurality of viscous materials of differentcolors, the sheet being formed into at least a portion of the kayak andhaving a surface presenting color effects including color gradationeffects resulting from combinations of the viscous materials, whereinsections of the extruded sheet are characterized by color bandsdiagonally oriented with reference to a longitudinal extent of theextruded sheet.

In accordance with another aspect, a sheet of extruded material made ofa plurality of viscous materials of different colors, the sheet having asurface presenting color effects including color gradation effectsresulting from combinations of the viscous materials, wherein sectionsof the extruded sheet are characterized by color bands diagonallyoriented with reference to a longitudinal extent of the extruded sheet.

All features of embodiments which are described in this disclosure andare not mutually exclusive can be combined with one another. Elements ofone embodiment can be utilized in the other embodiments without furthermention.

Other aspects and features of the present invention will become apparentto those ordinarily skilled in the art upon review of the followingdescription of specific embodiments of the invention in conjunction withthe accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

A detailed description of specific embodiments of the present inventionis provided herein below with reference to the accompanying drawings inwhich:

FIG. 1 illustrates a system for manufacturing plastic sheets, accordingto a non-limiting example of implementation of the present invention;

FIG. 2 depicts components of a flow rate controller that may be used inconnection with an extruder of the system of FIG. 1 ;

FIG. 3 depicts an electronic control element of the flow rate controllerof FIG. 2 in accordance with a non-limiting embodiment of the presentinvention;

FIGS. 4A and 4B are charts illustrating variations in a speed ofoperation of an extruder screw in order to cause variation in a flowrate in connection with an extruder of the system of FIG. 1 ;

FIG. 5A shows color effects that may be produced using extrudableplastic material using a system of the type shown in FIG. 1 in which theflow rate controller maintains a constant flow rate;

FIG. 5B shows color effects that may be produced using extrudableplastic material using a system of the type shown in FIG. 1 in which theflow rate controller varies the flow rate over time of the materialreleased by an extruder;

FIG. 6 depicts an example of a possible structural configuration for afeed block shown in FIG. 1 ;

FIG. 7 is a perspective view of a helical dynamic mixer;

FIG. 8 is a perspective view of a different type of dynamic mixer;

FIG. 9 depicts components of a controller configured to control adynamic mixer in connection with the system of Figure in accordance witha non-limiting embodiment of the present invention;

FIG. 10 depicts an electronic control element of the controller of FIG.9 in accordance with a non-limiting embodiment of the present invention;

FIG. 11A shows examples cross-sectional views of combined streams ofviscous material entering the dynamic mixer 108 of the system 100 shownin FIG. 1 in accordance with non-limiting examples of implementation,the examples including (a) a first viscous material (“A”) only; (b)first viscous material (“A”) and second viscous material (“D”); and (c)first viscous material (“A”), second viscous material (“D”) and thirdviscous material (“E”);

FIGS. 11B, 11C, 11D and 11E shows other examples of cross-sectionalviews of combined streams of viscous material entering the dynamic mixer108 of the system 100 shown in FIG. 1 in accordance with non-limitingexamples of implementation;

FIG. 12 illustrates a combined stream of viscous material as it exitsthe dynamic mixer in accordance with a non-limiting implementation;

FIGS. 13A and 13B depict sheets of plastic having surfaces presentingcolor effects including color gradation effects having undulating colorbands oriented along a longitudinal extent in accordance with non-limingexamples of implementation of the invention;

FIG. 13C depicts a tube of plastic with undulating color bands withcolor gradation effects, the undulations being oriented along alongitudinal extent of the tube in accordance with another non-limingexample of implementation of the invention;

FIGS. 13D and 13E depict sheets of plastic having surfaces presentingcolor effects including color gradation effects in which the colortransitions are oriented at an incline relative to a longitudinal extentof the plastic sheets in accordance with non-liming examples ofimplementation of the invention;

FIG. 14 is a flowchart illustrating a process for creating color effectsusing extrudable material according to an example of implementation ofthe present invention; and

FIG. 15 depicts a system for manufacturing plastic sheets according to avariant of implementation of the present invention;

FIG. 16A shows a kayak manufactured using plastic sheets of extrudedmaterial created using a process embodying aspects of the invention;

FIGS. 16B and 16C show top plan and side views respectively of astand-up paddle board (SUP) manufactured using plastic sheets ofextruded material created using a process embodying aspects of theinvention;

FIG. 17 illustrates effects of variations in rotational positions of adynamic mixer on color gradations effects in accordance with a specificexample of implementations of the invention.

In the drawings, embodiments of the invention are illustrated by way ofexamples. It is to be expressly understood that the description anddrawings are only for the purpose of illustration and are an aid forunderstanding. They are not intended to be a definition of the limits ofthe invention.

DETAILED DESCRIPTION

The present invention is directed to a process and apparatus forcreating color effects using extrudable material, such as plastic ormetal.

In the following examples of implementation, the present invention willbe described for use in creating color effects in extruded plasticmaterial. However, it is to be appreciated that the invention is notlimited to any particular type of material. Rather, the conceptsdescribed in the present document may be applied to different types andgrades of extrudable material.

FIG. 1 depicts a system 100 for manufacturing plastic sheets, accordingto a non-limiting example of implementation of the present invention.The system 100 shown is formed of several components, including a die102, a feed block 104, a first (primary) extruder 106 for providing afirst material (“A”) and one or more secondary extruders 120 ₁, . . . ,120 _(N), where the number N of secondary extruders 120 ₁, . . . , 120_(N) in the system 100 is at least one.

Note that, in alternative embodiments, the system 100 may include two ormore secondary extruders 120 ₁, . . . , 120 _(N).

Extruder 106 and each extruder 120 ₁, . . . 120 _(N) is operative to mixand heat plastic granules. The granules are heated to a predeterminedtemperature, sufficient to cause melting of the granules for producing ahomogeneous, viscous plastic mixture.

Examples of the different types of thermoplastics that can be extrudedinclude: LDPE, HDPE, ABS, polystyrene, polypropylene, acetates,butyrates, nylons, polyphenylene sulfides, acetals, polycarbonates andthermoplastic rubbers and polyesters, among other possibilities.

Typically, a controlled amount of colorant is added to the mixture inextruder 106 and in each extruder 120 ₁, . . . , 120 _(N), for obtainingviscous plastic mixtures of respective specific colors.

Different techniques, known in the art, may be used to color the plasticmixtures in the extruders 106 and 120 ₁, . . . , 120 _(N). In oneexample, colorant in the form of granules is added to and mixed with theplastic granules before they are fed into the extruders 106 and 120 ₁, .. . , 120 _(N) for melting. In another example, colorant in liquid formmay be fed into the extruders for mixing with the plastic granules.Alternatively, the non-recycled plastic granules themselves can bepre-colored such that it is not necessary to add colorant to themixture. In another alternative, recycled plastic granules of a specificcolor may be used in the extruders 106 120 ₁, . . . , 120 _(N), suchthat the addition of a colorant is not required.

In a specific practical implementation, the mixture “A” used in theprimary extruder 106 may be a translucent material and the mixture “D”in the secondary extruders 120 ₁ may be a mixture of a specific color.Similarly, the mixture “E” in another secondary extruder 120 _(N) may bea mixture of a specific color, which may be the same or distinct fromthe color of mixture “D” used in the secondary extruder 120 ₁.

The primary extruder 106 is configured to melt and mix the plasticgranules such that the mixture 110, which is released from extruder 106,is perfectly melted and homogeneous, both in temperature and in color,upon its exit from the extruder 106.

Similarly, a secondary extruder 120 is configured to melt and mix theplastic granules such that the mixture 122, which is released from asecondary extruder 120, is also perfectly melted and homogeneous, bothin temperature and in color, upon exit from the extruder 120.

Note that, with regard to the plastic mixture released by the primaryextruder 106, the term “melted” implies that the mixture ischaracterized by a viscous or semi-fluid flow. The plastic mixture 110released is also referred to herein as a flow of a first viscousmaterial 110. The extruder 106 releases the flow of the first viscousmaterial at a first rate of flow. The first rate of flow may be anysuitable rate flow depending on the type of extrudable material that isbeing created by the system 100, for example 400 kg/hr, 300 kg/hr, 100kg/hr or 50 kg/hr, among many other possibilities. As will be describedin greater detail later on in the present document, the flow of thefirst viscous material 110 may optionally be provided at a first rate offlow that can be caused to vary over time.

With regard to the plastic mixture output by the secondary extruders 120₁, . . . , 120 _(N), the term “melted” also implies that the mixture ischaracterized by a viscous or semi-fluid flow. The plastic mixture 122output by each extruder 120 is also referred to herein as a flow of a(second) viscous material 122. Each one of the secondary extruders 120may be set to a respective rate of flow, for example 400 kg/hr, 300kg/hr, 100 kg/hr, 50 kg/hr, 25 kg/hr or 10 kg/hr among many otherpossibilities. In the embodiment shown in FIG. 1 , during the creationof an extruded material, the secondary extruders 120 ₁, . . . , 120 _(N)may be set to operate such as to release the plastic mixtures 122 atrespective rates of flow that are kept substantially constant over time.It is however to be appreciated that, in alternate embodiments, therates of flow of material released by any of the secondary extruders 120₁, . . . , 120 _(N) may optionally be caused to vary over a time periodso that flows of both the viscous material released by the primaryextruder 106 and one or more of the secondary extruders 120 ₁, . . . ,120 _(N) are caused to vary over time. It is also to be appreciatedthat, in such alternative embodiments, the time intervals over which theviscous material released by the primary extruder 106 and the viscousmaterial released by or more of the secondary extruders 120 ₁, . . . ,120 _(N) are caused to vary need not be the same.

The structure and functionality of extruders are well known to thoseskilled in the art, and will not be described in further detail.

In the specific embodiment depicted in FIG. 1 , the primary extruder 106is in communication with an optional flow rate controller 152 configuredfor varying over time the rate of flow of the viscous material 110released by the primary extruder 106.

As depicted in FIG. 2 , the flow rate controller 152 associated with theprimary extruder 106 may include an electronic control element 606configured for causing the first rate of flow of the viscous material110 to vary over time. More specifically, and as shown in the specificembodiment depicted, the flow rate controller 152 may include a variablespeed motor 604 configured for operating at different speeds an extruderscrew 602 in the extruder 106. In this embodiment, the electroniccontrol element 606 includes a processor (not shown) programmed forreleasing control signals for controlling the speed of operation of thevariable speed motor 604, which in turn causes a variation in a speed ofrotation of the extruder screw 602 in the primary extruder 106. Anysuitable manner for controlling the speed of operation of the variablespeed motor 604 may be used and such manners are known in the art andwill not be described further here.

In a specific practical implementation, the flow rate controller 152 maybe configured for varying the first rate of flow over time at least inpart by causing the first rate of flow to oscillate between a lower flowrate threshold and an upper flow rate threshold over a certain timeinterval.

In specific practical implementation, the lower flow rate threshold, theupper flow rate threshold and/or the time period may be preset, forexample by a programmed element stored in the flow rate controller 152.Optionally, the lower flow rate threshold and/or the upper flow ratethreshold and/or the time period may be set (or modified) by an operatorof the system 100 in order to control at least in part visualcharacteristics of the color pattern in the stream of combined viscousmaterial that will be generated by the system 100. For example byshortening the time period, more compact visual wave-like effects may becaused in the resulting output stream of combined viscous material whileextending the time period may allow smoother/software visual wave-likeeffects to be created. The time period may be set to any suitableduration in dependence on the desired visual effect to be created in theextruded material. In non-limiting practical implementations, the timeinterval used tends to range between about 20 seconds and about 1minute. If we look now to the flow rate thresholds, increasing the upperflow rate threshold would tend to cause an increased volume of the firstviscous material (“A”) to be pushed towards the feed block 104, which inturn causes a greater amount of this substance to find itself in theresulting output stream of combined viscous material. Analogously,decreasing the lower flow rate threshold would tend to cause a reducedvolume of the first viscous material (“A”) to be pushed towards the feedblock 104, which in turn causes a lesser amount of this substance tofind itself in the resulting output stream of combined viscous material.Other variations can be made in the same manner to achieve differentcolor patterns.

In the embodiment depicted in FIG. 2 , the control of the first flowrate may be achieved by operating the variable speed motor 604 such asto cause the extruder screw 602 to vary its speed of rotation between anupper threshold and a lower threshold over a time period. FIGS. 4A and4B show charts illustrating variations of the speed of operation of theextruder screw 602 over time in connection with extruder 106. It is tobe appreciated that the examples shown in FIGS. 4A and 4B have been setforth for the purpose of illustration only and that many other suitablemanners of varying over time the rate of flow of the viscous material110 released by the primary extruder 106 may be contemplated and willbecome apparent to the person skilled in the art in view of the presentdescription.

Optionally in some embodiments, such as the specific one depicted inFIG. 3 , the electronic control element 606 of the flow rate controller152 may provide one or more user operable controls 700 702 732 forallowing a user to set the lower flow rate threshold and/or the upperflow rate threshold and/or the time interval in order to control atleast in part visual characteristics of the color pattern in the streamof combined viscous material exiting the system. The user operablecontrols 700 702 732 may include mechanically actuated switches thatallow a user to providing control commands to increase or decrease acorresponding flow control parameter (for e.g. the lower flow ratethreshold, the upper flow rate threshold or the time period).Optionally, display areas 704 708 734 may be provided showing values ofthe flow control parameters. It is to be appreciate that, although theelectronic control element 606 shown in FIG. 3 has been shown asincluding a dedicated control interface incorporating user operablecontrols, in alternative embodiment such control interface may beprovided on the display screen of a general purpose computing device incommunication with the electronic control element 606 and programmed todisplay a control interface including user operable controls of the typedescribed above.

It is to be appreciated that in alternative implementation, the primaryextruder 106 may be configured to release the flow of the flow of afirst viscous material 110 at a substantially constant flow rate. Insuch implementations, the flow rate controller 152 may be omitted.

In the context of the present invention, the extruder 106 and one ormore of extruders 120 ₁, . . . , 120 _(N) produce plastic mixtures 110122 of different colors and, optionally different viscosities. In aspecific, non-limiting example, the system 100 may include an extruder106 and one secondary extruder 120 ₁ which producing plastic mixtures110 122. In another example, the system 100 may include one primaryextruder 106 and two secondary extruders 120 ₁ 120 ₂ each of which isproducing a plastic mixture of a different color and, optionallydifferent viscosity.

In a practical embodiment, the plastic mixture 110 released by the(primary) extruder 106 is characterized by a first viscosity and theplastic mixture 122 released by the (secondary) extruder 120 has asecond viscosity. The first viscosity and the second viscosity may beessentially the same or may be distinct from one another. The firstviscosity may be lower (or higher) than the second viscosity. Inembodiments in which there may be multiple (secondary) extruders 120,the plastic mixtures released by each (secondary) extruder may have thesame (or similar) viscosity or, alternatively, may each have a distinctviscosity.

The use of materials having different viscosities may reduce an amountof color blending between the first color and the second color when thematerials are combined in the feedblock 104 and dynamic mixer 108 aswill be described later on in the present document. The respectiveviscosities of the materials released by the (primary) extruder 106 andthe (secondary) extruder(s) 120 may also be expressed in terms of highload melt index (HLMI). In this regard, the first viscous material maybe associated with a first high load melt index (first HLMI) and thesecond viscous material may be associated with a second high load meltindex (second HLMI). The first HLMI may be greater (or less) than thesecond HLMI.

It has been observed that using materials with differing HLMIs reducesthe amount of blending between the materials. The greater the differencein high load melt index, the lesser the amount of blending appears tooccur. The first HLMI may be at least about ten times (10×); at leastabout twenty times (20×); or at least about one hundred times (100×) thesecond HLMI. It is to be appreciated that, in practical implementations,the use of material having different viscosities may achieve differentcolor effects compared to the use of materials of uniform viscositiesand that such materials may be use alone or in combination with thevariation in flow rate of the flow released by the primary extruder 106.

The plastic mixture 110 released by the (primary) extruder 106 and theone or more plastic mixtures 122 released by the one or more (secondary)extruders 120 ₁, . . . , 120 _(N) are then provided to the feed block104.

The feed block 104 is configured for combining the flows 110 122 ofviscous plastic output by the different extruders 106 120 ₁, . . . , 120_(N) into a single patterned stream of combined viscous plastic, as willbe discussed further below.

In the example depicted, the feed block 104 is comprised of multiplesequence feed blocks 104 ₁ . . . 104 _(N) where each feed block injectsan additional stream of viscous material released by a respectivesecondary extruder 120 ₁, . . . , 120 _(N) into the stream of viscousmaterial released by first (primary) extruder 106 or released by aprevious feed block in the sequence. It will however be appreciated thatother configurations for feed block 104 are possible in alternativeimplementations. For example, feed block 104 may be comprised of asingle modules having N+1 input streams, where N corresponds for thenumber of secondary extruders 120 ₁, . . . , 120 _(N) in the system.

FIG. 6 illustrates a non-limiting example of a possible configurationfor the feed block 104, for the case in which the system 100 is formedof one primary extruder 106 and two secondary extruders 120 ₁ and 120_(N), wherein the primary extruder 106 releases a flow 110 of viscousmaterial of a greater size than the flows 122 released by each of thesecondary extruders 120 ₁ and 120 _(N). Thus, the feed block 104receives three distinct flows 110 122 of viscous plastic, each of whichis input to the feed block 104 from the associated extruder 106 and 120₁ and 120 _(N) via a respective feed port 270 200.

The feed block 104 also includes a programming section 202, whichreceives the flows 110 and 122 from the feed ports 270 200 intocorresponding channels 284 204. This programming section 202 isoperative to shape and position the flows 110 and 122 according to apredetermined pattern, whereby the flows undergo a programming of sortswithin the channels 284 204 in order to produce a desired pattern forthe stream of combined viscous material. In the example shown in FIG. 6, the channels 284 204 of the programming section 202 are designed toproduce a pattern of layers where the layer associated with the flow 110is shown as having a greater volume/size that the layers associated withthe flows 122 to accommodate the higher flow rate of the first viscousmaterial in the present example. It is to be appreciated that differentsizes, shapes and layouts for the channels 284 204 of the programmingsection 202 may also be used, in order to produce different patterns forthe stream of combined viscous material.

Note that the programming section 202 of the feed block 104 may bedesigned to divide a particular flow 110 or 122 into two or moresub-flows, for producing a different pattern for the stream of combinedviscous material. In a specific example, assume the feed block 104receives two flows 110 and 122, one that flow 110 is translucent incolor and that flow 122 is red in color. The programming section 202 maydivide the red flow 122 into two red sub-flows, and orient thesesub-flows such that the translucent flow 110 is sandwiched between thetwo red sub-flows, according to a particular layout and pattern.

Finally, the feed block 104 includes a transition section 206, operativeto fuse together the separate flows 110 and 122, for generating thepatterned stream of combined viscous material. As seen in FIG. 6 , thechannels 288 208 of the transition section 206 are oriented such thattheir output ports 210 are located immediately adjacent one another. Asthe distinct flows 110 and 122 exit the respective output ports 210, theflows of the viscous plastics, fuse together into a single, combinedstream of viscous plastic.

In the context of the present invention, the stream of combined viscousmaterial generated by the feed block 104 is characterized by zones ofmaterial having different colors and, optionally, different viscosities.More specifically, at least one zone of material may be formed of afirst viscous plastic material of a first color and first viscosity(material “A”) and another zone may be formed of a second viscousplastic of a second color and second viscosity (material “D”).

As mentioned above, the stream of combined viscous material released bythe feed block 104 may take on different patterns. Rather than ahorizontal layer pattern, the feed block 104 may combine the differentflows 110 122 according to a vertical layer pattern, a ring pattern, atube pattern or a pie chart pattern, among many other possibilities. Inthe case of the ring pattern, each separate flow 110 122 of viscousplastic may be formed into a concentric ring, where the rings ofdifferent colors and sizes are fused together to form a tube of combinedviscous plastic characterized by adjacent zones of different colors and,optionally, different viscosities. In the case of the tube pattern, theseparate flows 110 122 may be positioned with respect to one anothersuch that, when fused together, they form an elongate tube,characterized by adjacent zones of different colors and, optionally,different viscosities.

FIGS. 11A, 11B, 11C, 11D and 11E show examples of cross-sections ofcombined streams of viscous material that may be generated usingdifferent practical embodiments of the feed block 104.

For example, FIG. 11A shows examples of cross-sections including (a) afirst viscous material (“A”) only; (b) first viscous material (“A”) andsecond viscous material (“D”); and (c) first viscous material (“A”),second viscous material (“D”) and third viscous material (“E”). It is tobe understood that there is a myriad of other possible configurationsand that the examples here have been shown for the purpose ofillustration only.

Note that a generally uniform transition of the flows 110 122 from theextruders 106 120 to the feed ports 270 200 of the feed block 104, aswell as from one component to another within the feed block 104, withoutany brusque variations in the channel dimensions may assist in reducingthe likelihood of stagnation of the viscous plastic material within thefeed block 104.

The use of feed blocks in extrusion processes is well known in the artand, as such, additional details pertaining to the feed block structureand functionality will not be described in further detail herein.

Specific to the present invention, the stream of combined viscousmaterial released by the feed block 104 is fed through a dynamic mixerpipe 108. The dynamic mixer 108 is operative to act on the stream ofcombined viscous material for partially mixing the adjacent zones ofdifferent colors (and optionally different viscosities) in order tocreate color effects in the stream of combined viscous material.

Dynamic mixers are known in the industry to be useful for effectivelymixing fluids, by executing the operations of division of flow, radialmixing and flow reversal. The most common type of mixer is the helicalmixer, as seen in the example of FIG. 7 , which includes a series ofelements positioned adjacent another. Each element may be formed of arectangular plate twisted by 180 degrees, which splits the oncoming flowin half and then turns it through 180 degrees. Each element in theseries may be rotated 90 degrees with respect to the preceding element,so as to constantly subdivide the flow. When two fluids of differentcolors enter a helical mixer pipe, the dividing and overturning motionapplied to the fluids by the elements of the mixer results in a gradualblending of the two fluids. More specifically, as the fluids go alongthe curves of each element, they are rotated radially towards the pipewall, or rotated back to the center. Furthermore, as the fluids passfrom one element to the next, the fluids are bisected and they changedirection to the right or to the left, the force of inertia thatsuddenly occurs creating a strong flow reversal motion that results instirring and mixing of the fluids. It is to be appreciated that while ahelical mixer has been shown in certain figures and described in thepresent description, any suitable type of mixer may be used in alternateimplementations.

The color pattern in the stream released by the dynamic mixer 108 isconfigured at least in part based on a radial orientation of theelements of the dynamic mixer 108. The color pattern in the stream maybe altered by positioning the elements of the dynamic mixer 108 inalternative radial orientations by rotating the elements about a pivotaxis extending through the dynamic mixer 108 in a longitudinaldirection. The alternative radial orientations may be established basedon an internal structure of the dynamic mixer 108 such that upon exitingthe static mixer a desired effect may be achieved in the stream ofviscous material. In specific practical implementations, the alternativeradial orientations may be a rotation of about 45°, 90°, 135° or 180°measured from a reference radial orientation however other alternativeradial orientations may also be suitable for other dynamic mixers.

In some implementations, a specific radial orientation of the elementsof the dynamic mixer 108 may be set prior to initiating a process usingthe system 100 (shown in FIG. 1 ).

In some alternative implementations, the specific radial orientation ofthe elements of the dynamic mixer 108 may be dynamically modified over atime period during operation of the system 100 (shown in FIG. 1 ) tocause variations in the color pattern in the stream of combined viscousmaterial released by the dynamic mixer 108. More specifically, the colorpattern in the stream may be dynamically altered over time by varyingthe specific radial orientation of the elements of the dynamic mixer 108during the application of the dividing, overturning and combining motionto the stream of combined viscous material entering the dynamic mixer108. The varying of the specific radial orientation of the elements ofthe dynamic mixer 108 may be effected by performing a rotation of theelements of the dynamic mixer 108 about the pivot axis by a by apre-determined amount.

In the specific embodiment depicted in FIG. 1 , the dynamic mixer 108 isin communication with a dynamic mixer controller 180 configured forvarying over time the specific radial orientation of the elements of thedynamic mixer 108.

As depicted in FIG. 9 , the dynamic mixer controller 180 associated withthe dynamic mixer 108 may include an electronic control element 906configured for causing the specific radial orientation of the elementsof the dynamic mixer 108 to vary over time. More specifically, and asshown in the specific embodiment depicted, the dynamic mixer controller180 may include a motor 904 configured for rotating the elements of thedynamic mixer 108 about a pivot axis extending through the dynamic mixer108 in a longitudinal direction. The dynamic mixer controller 180 may beconfigured to cause the motor 904 to rotate the elements of the dynamicmixer 108 in a clock-wise and/or counter clock-wise direction. The motor904 may be a variable speed motor such as to allow the dynamic mixercontroller 180 to modify the speed at which the elements of the dynamicmixer 108 are being rotated. In this embodiment, the electronic controlelement 906 includes a processor (not shown) programmed for releasingcontrol signals for controlling the speed and direction of operation ofthe motor 904, which in turn causes a variation in an rotation amount,rotation direction and/or a speed of rotation of the elements of thedynamic mixer 108. Any suitable manner for controlling the speed ofoperation of the variable motor 904 may be used and such manners areknown in the art and will not be described further here.

In some specific practical implementations, the dynamic mixer controller180 may be configured for performing rotations of the elements of thedynamic mixer 108 by a pre-determined rotation amount repeatedly overtime, at regular or non-regular time intervals, during the applying ofthe dividing, overturning and combining motion to the stream of combinedviscous material. The pre-determined rotation amount may be a rotationby any suitable angle such as, for example, it may be a rotation by anangle of rotation greater than 0° and less than or equal to 360°;between 30° and 130°; between 45° and 110°. In a non-limiting example,the angle of rotation is about 90°. It is also to be appreciated thatthe pre-determined rotation amount may vary over time. For example, theelements of the dynamic mixer 108 may be rotated in a clock-wisedirection by a first angle in a first instance (say 30°) and then may berotated in a clock-wise direction by a second angle in a second instance(say 45°) and then may be rotated in a counter-clock-wise direction by athird angle in a third instance (say 15°).

In some specific practical implementations, the dynamic mixer controller180 may be configured for varying the rotational position of the dynamicmixer 108 to cause the rotational position of the elements to varysubstantially continuously over a time interval, for example byoperating the motor 904 at a substantially uniform/constant speed forthe time interval.

In some specific practical implementations, the dynamic mixer controller180 may be configured for causing the rotational position of theelements to vary between a first rotational position threshold and asecond rotational position threshold over a time interval. In specificpractical implementations, the first rotational position threshold maybe a rotational position of about 0°, 90°, 180°, 270° or 360° or anyother position, relative to reference position. The first rotationalposition threshold may be a rotational position of about of about 0°,90°, 180°, 270° or 360° or any other position, relative to a reference arotational position. In addition, the rotational position of theelements may be caused to vary between the first rotational positionthreshold and the second rotational position threshold over the timeinterval repeatedly during the applying of the dividing, overturning andcombining motion to the stream of combined viscous material. It is to beappreciated that while in the example presented the rotationalthresholds mentioned were described as being spaced in equal incrementsof 90°, this was done for the purpose of example only and that any otherrotational positions may be used and that these need not be spaced byincrements of 90° and need not be equally spaced.

In some specific practical implementations, the first rotationalposition threshold, the second rotational position threshold and/or thetime interval may be preset, for example by a programmed element storedin the dynamic mixer controller 180. Optionally, the first rotationalposition threshold and/or the second rotational position thresholdand/or the time interval may be set (or modified) by an operator of thesystem 100 in order to control at least in part visual characteristicsof the color pattern in the stream of combined viscous material thatwill be generated by the system 100.

For example by shortening the time interval, more compact (higherfrequency) for the visual undulating color bands may be caused in theresulting output stream of combined viscous material while extending thetime interval may allow smoother/softer (lower frequency) for the visualundulating color bands to be created. The time interval may be set toany suitable duration in dependence on the desired visual effect to beeventually created in the extruded material. In non-limiting practicalimplementations, the time interval used tends to range between about 0.5second and about 10 seconds however it will be appreciated that anysuitable time interval may be used in practical implementations independence of a desired visual affect to be achieved. If we look now tothe first and second rotational position thresholds, increasing themagnitude of the difference between the first and second rotationalposition thresholds generally translates into undulating color bandswith wave-like effects with correspondingly greater amplitude in theresulting stream to be pushed towards the die 102. Analogously,decreasing magnitude of the difference between the first and secondrotational position thresholds generally translates into undulatingcolor bands with wave-like effects with correspondingly smalleramplitude in the resulting stream to be pushed towards the die 102.Other variations can be made in similar manners to achieve differentcolor patterns.

The controller 180 may be configured to drive the elements of thedynamic mixer 108 at a rotational speed set to correspond to apre-determined rotational speed. In specific practical implementationsthe pre-determined rotational speed may be at least 1°/second, at least5°/second or at least 20°/second, while in other implementations it maybe no more than 20°/second, no more than 5°/second or no more than1°/second.

In some specific practical implementations, the dynamic mixer controller180 may be configured for causing the rotation of the elements to beperformed at a speed that varies over time between an upper rotationalspeed threshold and a lower rotational speed threshold over a timeperiod. In some specific non-limiting embodiments, the controller of thestatic mixer 108 may be configured for causing the rotation of theelements to be performed at a speed that varies over time in accordancewith a sinusoidal function. Increasing or decreasing a speed of rotationmay typically have the effect of increasing/decreasing the frequency ofvisual pattern changes in the undulating color bands in the resultingoutput stream of combined viscous material.

Optionally in some embodiments, such as the specific one depicted inFIG. 10 , the electronic control element 906 of the flow rate controller180 may provide a control interface having one or more user operablecontrols 950 952 954 962 964 for allowing a user to set the firstrotational position threshold and/or the second rotational positionthreshold and/or the time interval and/or rotational direction patternin order to control at least in part visual characteristics of the colorpattern in the stream of combined viscous material exiting the system.The user operable controls 950 952 954 962 964 may include mechanicallyactuated switches and or data fields that allow a user to providingcontrol commands to modify a corresponding parameter (for e.g. the firstrotational position threshold, the second rotational position threshold,the time interval or the rotational direction pattern). It is to beappreciated that while the user control interface has been presented asincluding specific types of operable controls 950 952 954 962 964 forallowing a user to modify specific parameters of operation of thedynamic mixer 108, it is to be appreciated that alternative embodimentsof the control interface may include fewer or additional operablecontrols so that different sets of parameters of operation canalternatively be specified by a user. For example, in some alternativeimplementations (not shown in the figures) the control interface mayinclude one or more user operable controls for allowing a user tospecify one or more rotational speeds for the dynamic mixer, optionallyin combination with one or more time intervals and/or one or more anglesor rotations and/or direction of rotation. Many other alternative willbecome apparent to the person skilled in the art in view of the presentdescription and as such will not be described in further detail here.

Optionally, display areas 960 958 956 may be provided showing values ofthe control parameters. It is to be appreciate that, although theelectronic control element 906 shown in FIG. 10 has been shown asincluding a dedicated control interface incorporating user operablecontrols, in alternative embodiment such control interface may beprovided on the display screen of a general purpose computing device incommunication with the electronic control element 906 and programmed todisplay a control interface including user operable controls of the typedescribed above. In addition, or alternatively, the control interfacemay be incorporated in the same physical device of a control interfaceused in connection with the flow rate controller 152 (shown in FIG. 1 ).

Note that, for fluids of different types and/or viscosity, a differentnumber of elements may be required in the dynamic mixer 108 in order toobtain a complete mixing of the two or more fluids from entry into thedynamic mixer 108 to output from the dynamic mixer.

Different types of dynamic mixers exist for uniformly mixing fluids inorder to produce a homogenous mixture, such as the example shown in FIG.8 . Such dynamic mixers are typically all designed around the sameprinciple, notably passing the viscous fluids through a series ofelements that cause the fluids to undergo different flow patternsresulting in the mixing of the fluids.

Under the present invention, the dynamic mixer 108 may be characterizedby a specific number of elements, such that, upon exit from the dynamicmixer 108, only a partial mixing of the different colored zones of thestream of combined viscous material has occurred, creating a blended,gradation in the colors of the stream of combined viscous material.

More specifically, upon entering the dynamic mixer pipe 108, the streamof combined viscous material includes adjacent zones of first and secondcolors (and optionally first and second viscosities) respectively. Thedynamic mixer 108 is operative to mix together a portion of the zonessuch that, when the stream of combined viscous material exits thedynamic mixer 108, the stream of combined viscous material may becharacterized by zones of a third color, different from the first andsecond colors. It should be understood that the zones of color that exitthe dynamic mixer 108 are not necessarily clearly defined zones. In afirst embodiment there can be a sharp transition between the color ofone zone and the color of an adjacent zone, thereby creating clearlydefined zones. However in an alternate embodiment, there can be a slowcolor gradation from the color of one zone to the color of an adjacentzone, such that the border between the two zones is not clearly defined.In addition, the shapes of the zones can vary. For example, the zonescan be substantially straight, or can be wavy or curved. Likewise, thezones can be horizontally oriented, vertically oriented, or diagonallyoriented at any angle between horizontally oriented and verticallyoriented.

Typically, when the stream of combined viscous material exits thedynamic mixer 108, the third zone of a third color is a combination ofthe colors of the first and second zones. For example, if the stream ofcombined viscous material that enters the dynamic mixer 108 includes afirst zone that is yellow and a second zone that is red, then typically,the stream of combined viscous material that exits the dynamic mixer mayinclude a third zone that is a shade of orange.

Alternatively, when the stream of combined viscous material exits thedynamic mixer 108, the third zone of the third color is not necessarilylocated between the first and second zones of the first and secondcolor. Instead, it is possible that the third zone of the third color islocated between two zones of the first color, or two zones of the secondcolor. For example, if the stream of combined viscous material thatenters the dynamic mixer 108 includes a first zone that is white and asecond zone that is blue, then the stream of combined viscous materialthat exits the dynamic mixer may have a third zone that is a lightershade of blue. As such, it should be understood that for the purposes ofthe present invention, the third color can be a lighter shade of one ofthe first and second colors. In addition, it is possible that the streamof combined viscous material that exits the dynamic mixer 108 will notinclude a zone of white, and that instead the stream of combined viscousmaterial includes a zone of the light blue located between two zones ofthe blue that entered the dynamic mixer.

Note that the dynamic mixer pipe 108 may include two or more dynamicmixers, for acting simultaneously on different portions of the stream ofcombined viscous material as the stream passes through the dynamic mixerpipe 108.

Take for example the case where the system 100 includes a first extruder106 producing a flow 110 of translucent viscous plastic, a secondextruder 120 ₁ producing a flow 122 of blue viscous plastic and a thirdextruder 120 ₂ producing a flow 122 of yellow viscous plastic. Assumethat the feed block 104 is operative to combine these three separateflows 110 122, characterized by: (a) a zone of yellow; (b) a zone ofblue and (c) a translucent zone. With reference to FIG. 11A (c) and FIG.12 , as this combined stream passes through the dynamic mixer pipe 108,the three zones of color are partially mixed together. Thus, otherzones, green in color, may be created around the yellow and blue zonesof the stream as well as around the translucent zones. Additional zonesof color may also be created, located between the green zone and theyellow zone, as well as between the green zone and the blue zone. Uponits exit from the dynamic mixer 108, the stream of combined viscousmaterial of viscous plastic may include a gradation in color from yellowto blue, and includes zone of different colors.

Note that the length of the dynamic mixer 108 that is necessary toobtain a partial mixing of the different colored zones of the stream ofcombined viscous material of viscous plastic may vary for differentimplementations of the system 100. The present invention is not limitedto any specific length, or number of elements, for the dynamic mixerpipe 108.

The selection of an appropriate dynamic mixer 108 may be based oncertain predetermined parameters, including the diameter, length,orientation of the elements themselves within the dynamic mixer 108, therange of rotational speeds of the elements of the dynamic mixer 108 andthe possible direction(s) of the rotation of the dynamic mixer 108.Furthermore, the determination of the appropriate dimensions for thedynamic mixer 108 will depend on the type of plastic material in usewithin the system 100, as well as the respective rate of flow for eachextruder 106 120 ₁, . . . , 120 _(N) and the total rate of flow for thestream of combined viscous material output by the feed block 104.

Note that as the elements of the dynamic mixer 108 adopt differentorientations with respect to the longitudinal plane of the stream ofcombined viscous material result in different patterns of colorgradation in the stream of combined viscous material at the output ofthe dynamic mixer pipe 108. For example, in the case of a helicaldynamic mixer 108, when the last element of the dynamic mixer 108 isoriented horizontally with respect to the plane of the stream ofcombined viscous material, the dynamic mixer 108 will tend to producelongitudinal bands of color in the stream of combined viscous material.In contrast, when the last element is oriented vertically with respectto the plane of the stream of combined viscous material, the dynamicmixer 108 will tend to produce vertical or diagonal bands of color inthe stream of combined viscous material. As elements of the dynamicmixer 108 are rotated, the bands of color in the stream of combinedviscous material will vary between horizontal and vertical bands and mayresult in creating undulating color bands of combined viscous material.The angle, direction, speed and pattern of rotation of the elements ofthe dynamic mixer 108 may each impact the pattern of color gradation inthe stream of combined viscous material at the output of the dynamicmixer pipe 108. In some implementations, at the exit of the dynamicmixer 108, the color bands may be twisted with one another in the streamof combined viscous material as a result of rotating of the elements ofthe dynamic mixer 108.

Furthermore, in some implementations, different rates of flow for thedifferent extruders 106 120 ₁, . . . , 120 _(N), may produce coloredzones of different sizes within the stream of combined viscous material.Thus, the resulting color pattern achieved in the stream of combinedviscous material by the dynamic mixer 108, including both size and colordominance, may be dependent on the respective rate of flow of theextruders 106 120 ₁, . . . , 120 _(N), as well as on the behavior of thedynamic mixer 108.

In a specific, non-limiting example, in order to create a sheet ofplastic having undulating color bands of red-orange-yellow once it hasexited the dynamic mixer 108, a first extruder having a 3^(1/2) inchdiameter at 50 rpm may be supplied with new plastic granules and 4% redcolorant, and a second extruder having a 1^(1/2) inch diameter at 75 rpmmay be supplied with new plastic granules and 4% yellow colorant. Fromthe extruders, viscous flows of red and yellow plastic are fed into afeedblock that forms the flows of red and yellow plastic into a streamof adjacent zones, which it feeds into a helical dynamic mixer having a2^(1/2) inch diameter made of 3 elements. In this specific non-limitingexample, the specific radial orientation of the elements of the dynamicmixer 108 may be caused to vary repeatedly between a first rotationalposition threshold and a second rotational position threshold over atime interval by sequentially performing a clockwise andcounter-clockwise rotation of the elements between these thresholds inorder to create a stream having undulating color bands oriented along alongitudinal extent of the stream.

In another specific, non-limiting example, in order to create a sheet ofplastic having a blue, white and light blue appearance once it hasexited the dynamic mixer, a first extruder having a 3^(1/2) inchdiameter is supplied with new plastic granules and 2% white colorant,and a second extruder having a 1^(1/2) inch diameter at 70 rpm issupplied with new plastic granules and 4% blue colorant. Optionally, thefirst extruder may be operated at a variable speed that fluctuatesbetween about 12 rpm and 60 rpm over a 20 second time interval in orderto further vary the color pattern of the eventual sheet. From theextruders, the flows of white and blue viscous plastic are fed into afeedblock that forms the two flows into a three layer stream of blue,white and blue which it feeds into a helical dynamic mixer having a2^(1/2) inch diameter made of 6 elements. The specific radialorientation of the elements of the dynamic mixer may be caused to varycontinuously by performing a clockwise (or counter-clockwise rotation)of the elements in order to create a stream having color bands orientedat an incline along a longitudinal extent of the stream.

The die 102 receives the stream of combined viscous material from thedynamic mixer pipe 108, and is operative to shape the stream of combinedviscous material into its final product form, such as a sheet or a tube,among many other possibilities. In the non-limiting example shown inFIG. 1 , the die 102 is operative to produce sheets of plastic 112 fromthe stream of combined viscous material. Different shapes and sizes ofdies may be used within the system 100 to generate different forms andtypes of plastic products. The structure and functionality of such diesare well known to those skilled in the art, and as such will not bedescribed in further detail herein.

FIGS. 13A, 13B and 13C illustrate examples of products that may beformed by the die 102. In FIGS. 13A and 13B show examples of a sheet ofplastic resulting from a three-color (translucent, yellow and blue)extrusion process. In its final product form, the sheet of plastic ischaracterized by color gradation effects including translucent zones(the color “A” from the first extruder 106), as well as undulating colorbands of blue (the color “D” from extruder 120 ₁), of yellow (the color“E” from extruder 120 _(N)) and green (resulting from a partial blendingof color “D” and color “E”). In some specific implementations, sectionsof the sheet of extruded material taken along a longitudinal axisextending along the length of the extruded sheet may be characterized byundulating color bands oriented along a longitudinal extent of the sheetto create a wave-like pattern. In some other specific implementations,sections of the sheet of extruded material taken along a longitudinalaxis extending along the length of the extruded sheet may becharacterized by create color bands oriented at an incline along alongitudinal extent of the sheet to create a pattern with diagonallyoriented color bands.

In FIG. 13C is shown an example of a tube of plastic resulting from thesame three-color extrusion process.

FIGS. 13D and 13E illustrate other examples of products that may beformed by the die 102.

In FIGS. 13A and 13B, the color bands are shown as undulating and insome section are generally diagonal relative to the longitudinal extentto the sheet. FIGS. 13D and 13E show examples of a sheet of plasticresulting from a three-color (translucent, yellow and blue) extrusionprocess. In its final product form, the sheet of plastic ischaracterized by color gradation effects including translucent zones(the color “A” from the first extruder 106), as well as undulating colorbands of blue (the color “D” from extruder 120 ₁), of yellow (the color“E” from extruder 120 _(N)) and green (resulting from a partial blendingof color “D” and color “E”). In the specific example illustrated, thecolor transition or gradation occurs along an axis that is generallydiagonal to the longitudinal extent to the sheet.

The product resulting from the extrusion process described in thepresent document, such as the sheet or tube of plastic, may be used asis, in different applications. For example, the sheets of plastic may becut out to form tobogganing carpets, also referred to as crazy carpets.Alternatively, the product resulting from the extrusion process may bethermoformed into different shapes or final products. For example, thesheets of plastic characterized by undulating color band color gradationeffects may be thermoformed into pedal boats, kayaks, canoes, stand-uppaddle boards or other similar watercraft products. They may also bethermoformed into recreational products, such as toboggans and pools,among many other possibilities. Whether thermoformed or not, a mainadvantage of the extruded product resulting from the above-describedextrusion process is to provide an esthetically appealing appearance tothe consumer or user.

FIG. 16A shows a kayak manufactured using one or more plastic sheets ofextruded material with undulating color band color gradation effectscreated using a process embodying aspects of the invention described inthe present document.

More specifically, a kayak of the type depicted in FIG. 16A may bemanufactured by molding two or more of the manufactured sheets ofextruded material using thermoforming to shape the two of moremanufactured sheets into a kayak shape. In such process, one or more ofthe two or more of the manufactured sheets may have color effectscreated using a process embodying aspects of the invention described inthe present document.

FIGS. 16B and 16C show top plan and side views respectively of astand-up paddle board (SUP) manufactured using plastic sheets ofextruded material created using a process embodying aspects of theinvention described in the present document.

FIG. 14 is a flowchart illustrating a process that may be implemented bythe system 100 for creating color gradation effects in extruded plasticmaterial.

As shown, at step 1200, a flow of a first viscous material of a firstcolor is provided through the primary extruder 106 (shown in FIG. 1 ).Optionally in some implementations, when providing the first viscousmaterial (material “A”), the first rate of flow may be caused to varyover time. Varying the rate of flow of the first viscous material overtime may allow modulating over time an amount of the first viscousmaterial (material “A”), relative to an amount of the second viscousmaterial (material “D”) that finds itself in the stream of combinedviscous material at different moments in time, which may allow the coloreffects created to vary over time.

FIG. 5A shows color effects that may be produced using extrudableplastic material using the system 100 in which the flow rate controller152 maintains a generated constant first flow rate in connection withextruder 106 (in other words no flow rate variation is applied toextruder 106). FIG. 5B shows color effects that may be produced usingextrudable plastic material using the system 100 in which the flow ratecontroller 152 varies the flow rate of the extrudable material 1101. Ascan be observed, the modulation of the flow rate may allow creatingwave-like color gradation effects in the resulting plastic material.

In one of the non-limiting practical embodiments contemplated, the firstviscous material “A” is a base or carrier color. For example, the firstviscous material “A” may be a translucent material and/or a neutralcolor such as a white (or off white), grey or any other suitable base ofcolor.

At step 1202, which is performed concurrently with step 1200, a flow ofa second viscous material of a second color, different from the firstcolor, is provided through one of secondary extruders 120 (shown in FIG.1 ). In some specific implementations, when providing the second viscousmaterial (material “D”), the second rate of flow is kept substantiallyconstant over time. It is however to be understand that this need not bethe case in all implementations and that the second flow rate may alsobe caused to vary over time in a manner similar to that described abovewith reference to the flow of the first viscous material.

In some specific practical implementations, the second rate of flowassociated with the second viscous material of the second color may belower than the first rate of flow. In such implementations, the firstviscous material (“A”) constitutes a larger portion of the resultingstream of combined viscous material than the second viscous material(“D”). In specific practical implementations, the second rate of flowmay be no more than 50% of the first rate of flow, preferably no morethan 30% of the first rate of flow and more preferably no more than 20%of the first rate of flow.

In one of the non-limiting practical embodiments contemplated, thesecond viscous material “D” is an accent color intended to be carried bythe base (or carrier color) of material “A”. For example, the secondviscous material “D” may be a bright colored material and such as a red,blue, pink, green, yellow or any other color that may add visualinterest to the base (or carrier color) of material “A”.

In some implementations, the second viscous material “D” provided atstep 1202 may have a viscosity that is distinct from the viscosity ofthe first viscous material “A” to reduce an amount of color blendingbetween the first color and the second color in the stream of combinedviscous material.

At step 1204, the first and second flows are combined together in thefeed block 104 (shown in FIG. 1 ) in a predetermined pattern to form astream of combined viscous plastic.

Next, at step 1206, the stream of combined viscous plastic generated atstep 1204 is fed through the dynamic mixer 108 (shown in FIG. 1 ), whichis configured to partially mix the first viscous material (“A”) and thesecond viscous material (“D”) such that upon exiting the dynamic mixer,the first material of the first color and the second material of thesecond color form a color pattern in the stream of combined viscousmaterial. In some cases, the color pattern created includes zones of thefirst color, zones of the second color and (optionally) zones of a thirdcolor, different from the first and second colors. The third color istypically a blend between the first color and the second color. In somespecific implementations, the zones of different color are in the formof color bands and may include a first band of the first color, a secondband of the second color and a third band of the third color. In someimplementations, at the exit of the dynamic mixer 108, the first band,the second band and the third band are twisted with one another in thestream of combined viscous material and result in creating color bandsof combined viscous material that may be diagonally oriented relative toa longitudinal extent of the stream.

The effects of the varying rotational position of the dynamic mixer 108on the color bands may be more clearly understood with reference to FIG.17 . As depicted, as the rotational position of the dynamic mixer 108changes (illustrated on the left by the orientation of the radialoriental flight 1700), the order in which the first “A” color, second“D” color and third “E” color will appear on the plastic sheet will alsochange (as illustrated on the right of the Figure). In the exampledepicted as the radial orientation of the dynamic mixer 108 changes, thecolor bands (“A”, “D” and “E”) will diagonally transition (relative tothe longitudinal extent of the sheet) until one or more of the bandsdisappear along a side (see color E on the left of the sheet whichdisappears in the image (3)).

In cases where, the second viscous material “D” provided at step 1202has a viscosity that is distinct from the viscosity of the first viscousmaterial “A”, colors may tend to remain more true to the original firstand second colors, and exhibit less color blending, than in cases wherethe viscosities of the first and second viscous materials aresubstantially the same.

Note that the above process may be applicable to various differentsuitable types of extruded material, and is not limited to plasticapplications.

FIG. 15 depicts a system 800 for manufacturing plastic sheets, accordingto an alternative example of implementation of the present invention. Asshown, system 800 is used for manufacturing plastic products, such asplastic sheets, with color effects being provided in one or more surfacelayers of the product. In this case, extruder 806 ₁, which includesextruders 816, 860 ₁, . . . , 860 _(N), in combination with the feedblock 804 (which in this example is comprises of feed block sequence 804₁ . . . 804 _(N)) and the dynamic mixer 808 connected to controller 880,produces a stream of combined viscous plastic 810 ₁ characterized bycolor effects, in a similar manner as described above with regard to thesystem 100 (shown in FIG. 1 ).

This stream 810 ₁ is then fed into a combining device where it iscombined with the separate flows 800 of viscous plastic output by theextruders 806 ₂, . . . , 806 _(N). In the specific example shown in FIG.15 , the combining device includes the feed block 812. The feed block812 produces a co-extruded stream of viscous plastic 810 ₂, having atleast one layer, typically a surface layer, characterized by coloreffects. The die 814 then receives this co-extruded stream 810 ₂, and isoperative to mold the plastic stream into its final form, for example asheet or a tube.

Note that the feed blocks 804 and 812 may be similar in structure andfunctionality to that described above with regard to the feed block 104.

In an alternative embodiment wherein the die 814 is configured tocombine the streams from the dynamic mixer pipe 808 and the extruders806 ₂ 806 _(N) into a co-extruded sheet prior to forming the sheet intoits final form, the feedblock 812 can be omitted, and the combiningdevice may simply include the die 814.

Thus, in this variant example of implementation, plastic products areformed in which the color effects may be limited to an outer surface ofthe product. Note that, in this case, one or more of the extruders 806₂, . . . 806 _(N) may be fed with recycled plastic granules, if therespective one or more layers of plastic generated by these extrudersare not visible on the finished product. Alternatively, each of theextruders 806 ₂, . . . 806 _(N) may be producing a plastic mixture of apredetermined and specific color, depending on the specific applicationsand end products being formed.

Alternatively, the die 814 may be provided with multiple feed ports,such that the die 814 itself could directly receive the stream ofviscous plastic 810 ₁ from the dynamic mixer 808, as well as the flows800 from the extruders 806 ₂, . . . 806 _(N). Thus, the die 814 wouldact to combine the stream 810, and the flows 800 into the co-extrudedstream of viscous plastic 810 ₂, after which the die 814 would shape thestream 810 ₂ into the final product form. Note that, in this case, thedie 814 takes on the responsibility of the feed block 812, which is nolonger required within the system 800.

Although various embodiments have been illustrated, this was for thepurpose of describing, but not limiting, the invention. Variousmodifications will become apparent to those skilled in the art and arewithin the scope of this invention, which is defined more particularlyby the attached claims.

The foregoing is considered as illustrative only of the principles ofthe invention. Since numerous modifications and changes will becomereadily apparent to those skilled in the art in light of the presentdescription, it is not desired to limit the invention to the exactexamples and embodiments shown and described, and accordingly, suitablemodifications and equivalents may be resorted to. It will be understoodby those of skill in the art that throughout the present specification,the term “a” used before a term encompasses embodiments containing oneor more to what the term refers. It will also be understood by those ofskill in the art that throughout the present specification, the term“comprising”, which is synonymous with “including,” “containing,” or“characterized by,” is inclusive or open-ended and does not excludeadditional, un-recited elements or method steps.

Unless otherwise defined, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this invention pertains. In the case of conflict, thepresent document, including definitions will control.

Although the present invention has been described in considerable detailwith reference to certain embodiments thereof, variations andrefinements are possible and will become apparent to the person skilledin the art in view of the present description. The invention is definedmore particularly by the attached claims.

What is claimed is:
 1. A process for creating color effects usingextrudable material, said process comprising: a) providing a flow of afirst viscous material of a first color; b) providing a flow of a secondviscous material of a second color different from the first color; c)combining in a predetermined pattern the flow of the first viscousmaterial and the flow of the second viscous material to form a stream ofcombined viscous material, the stream comprising a first band of thefirst color and a second band of the second color, the second band beingadjacent to the first band; d) feeding the stream of combined viscousmaterial through a dynamic mixer configured for applying a dividing,overturning and combining motion to said stream of combined viscousmaterial to partially mix the first viscous material and the secondviscous material, such that upon exiting the dynamic mixer, the firstviscous material of the first color and the second viscous material ofthe second color form a color pattern in the stream of combined viscousmaterial, wherein said dynamic mixer has elements configured foracquiring a specific radial orientation in a range of radialorientations, said process comprising varying the specific radialorientation of the elements of the dynamic mixer by performing clockwiseand counter-clockwise rotations of the elements of the dynamic mixerduring the applying of the dividing, overturning and combining motion tothe stream of combined viscous material to cause variations in the colorpattern in the stream of combined viscous material to form an extrudedmaterial having a surface that presents color gradation effects havingan undulating color pattern oriented along a longitudinal extent of theextruded material.
 2. The process as defined in claim 1, wherein in thestream of combined viscous material the first band and second bandremain and the stream of combined viscous material further comprises athird band of a third color that is different from the first and secondcolors.
 3. The process as defined in claim 2, wherein the first band,the second band and the third band are twisted with one another in thestream of combined viscous material.
 4. The process as defined in claim1, wherein varying the specific radial orientation of the elements ofthe dynamic mixer includes performing a rotation of the elements of thedynamic mixer by a predetermined amount to vary the specific radialorientation of the elements of the dynamic mixer during the applying ofthe dividing, overturning and combining motion to the stream of combinedviscous material.
 5. The A process as defined in claim 4, wherein therotation of the elements of the dynamic mixer by the pre-determinedamount is performed repeatedly over time during the applying of thedividing, overturning and combining motion to the stream of combinedviscous material.
 6. The process as defined in claim 5, wherein therotation of the elements of the dynamic mixer by the pre-determinedamount is performed repeatedly at regular intervals over time during theapplying of the dividing, overturning and combining motion to the streamof combined viscous material.
 7. The process as defined in claim 4,wherein the rotation of the dynamic mixer by the pre-determined amountis a rotation by an angle of rotation greater than 0° and less than orequal to 360°.
 8. The process as defined in claim 1, further includesvarying a rotational position of the dynamic mixer over time includingcausing the rotational position to vary substantially continuously overa time interval between a first rotational position threshold and asecond rotational position threshold.
 9. The process as defined in claim8, wherein said process comprises altering at least one of the firstrotational position threshold and the second rotational positionthreshold in order to cause variations in the color pattern in thestream of combined viscous material.
 10. The process as defined in claim9, wherein altering the at least one of the first rotational positionthreshold and the second rotational position threshold includesmodifying the at least one of the first rotational position thresholdand the second rotational position threshold at least in part based oncontrol commands provided by a user through a control interface.
 11. Theprocess as defined in claim 1, wherein the rotational position of thedynamic mixer has a rate of change over time defining a rotational speedof the dynamic mixer, wherein the rotational speed is greater than zeroduring the applying of the dividing, overturning and combining motion.12. The process as defined in claim 11, wherein the rotational speed ofthe dynamic mixer remains substantially constant over time during theapplying of the dividing, overturning and combining motion.
 13. Theprocess as defined in claim 11, wherein the rotational speed of thedynamic mixer varies over time during the applying of the dividing,overturning and combining motion.
 14. The process as defined in claim11, said process comprising processing control commands provided by auser over a control interface to set the rotational speed of the dynamicmixer.
 15. The process as defined in claim 1, wherein: a) the flow ofthe first viscous material is associated with a first rate of flow,wherein providing the flow of the first viscous material of the firstcolor includes varying the first rate of flow over time; and b) the flowthe flow of the second viscous material is associated with a second rateof flow.
 16. The process as defined in claim 1, wherein after applyingthe dividing, overturning and combining motion, said process includesthe step of forming said stream of combined viscous material into asheet.
 17. The process as defined in claim 1, wherein after applying thedividing, overturning and combining motion, said process includes thestep of forming said stream of combined viscous material into a tube.18. The process as defined in claim 1, wherein after applying thedividing, overturning and combining motion, feeding the stream ofcombined viscous material through a die for forming a sheet of materialcomprising undulating color bands oriented along a longitudinal extentof the sheet.